I am not convinced he could have gotten the wall funded in 2017-2018 because he could not martial sixty votes in the Senate.
What really strikes me about that period was it was an opportunity to actually try to move the wall through the legislative process properly. rather than making it a bargaining chip in a hostage negotiation.
Yes Trump wants to the wall but do we know what it is actually be, where it will be built, actual cost, schedule to complete and the number of Eminent Domain claims the federal government intends to make to get the land?
What should have happened was the introduction of a bill in Congress, followed by hearing and debate that would have given shape to what the wall actually is, what it will cost and how it will be financed. Compromises to gain support could have been made.
Only this is a fantasy because as soon as any compromise is disgusts, the representatives of Trump’s base start to shout AMNESTY and all negotiation stops.
There probably was no way to get the wall through a normal democratic process and so we are in this current mess.